Octane requirements

I've got a stock 5.9 with ede intake, holley 750dp, accel distributor, MSD 6al, 3.23 gears.
I've got the timing set at 10 initial 30 total. It runs strong on 87 but will ping doing 3rd gear burnouts, after the tires start to grab :usflag:
I ordered a spring kit to bring in the mechanical advance as late as possible.